1. Field of the Invention
The invention relates to a method of forming non-woven flooring backing by the beater-saturated method in which the white water does not accumulate ammonium sulfate or multivalent cations which interfere with the precipitation process.
2. Description of the Prior Art
U.S. Pat. No. 2,375,245-Pretzel teaches the pretreatment of a papermaking fibrous slurry with alum and ammonia to form aluminum hydroxide in and around the papermaking fibers so that a subsequently adder binder latex will without further precipitation agent addition, precipitate and act as a binder during the sheet-laying process. U.S. Pat. No. 2,599,092-Craig teaches the addition of calcium chloride to a slurry of cellulosic fiber stock followed by the addition of sodium carbonate to precipitate calcium carbonate within the fibers in order to form a stiffer board. U.S. Pat. No. 3,082,145-Kao teaches a process of simultaneously coating cork granules and fibers with a coating material which may be a rubber latex. The process calls for pretreating with a salt which may be alum and adding an alkali which may be sodium carbonate or sodium hydroxide to a pH of approximately 5; no aluminum hydroxide appears to be formed. A latex is then added followed by the addition of a latex coagulant such as alum. U.S. Pat. No. 3,549,485-Eckert teaches a method of forming a mineral fiber-clay ceramic board by adding aluminum sulfate to a slurry of the mineral fiber and clay and then adding a deflocculant such as sodium carbonate or sodium hydroxide. And then there is U.S. Pat. No. 123747-Tiemann which issued Feb. 13, 1872. Here a papermaking slurry is pretreated with alum and followed by a treatment with "freshly-burned lime which has been previously slacked" in order to form a precipitate of "hydrate of alumina", doubtless aluminum hydroxide.